fix custom validation and include custom validation example

examples/README.md

@@ -4,18 +4,19 @@ you can view the source code within the folder or visit code sand box to see how
 
 | Name                        | Link                                |
 | --------------------------- | ----------------------------------- |
+| Array Fields                | https://codesandbox.io/s/6j1760jkjk |
+| Async Submit Validation     | https://codesandbox.io/s/xrjv48o0qp |
+| Async Field Validation      | https://codesandbox.io/s/m5pj55yj7x |
 | Basic                       | https://codesandbox.io/s/yj07z1639  |
 | Basic Validation            | https://codesandbox.io/s/rwpz2jn6ln |
-| Custom Input                | https://codesandbox.io/s/72j69vnk1x |
-| Register Error Messages     | https://codesandbox.io/s/o766kp4z05 |
+| Custom Validation           | https://codesandbox.io/s/8n937m64o9 |
 | Conditional Fields          | https://codesandbox.io/s/13ykqx4wx7 |
-| Async Submit Validation     | https://codesandbox.io/s/xrjv48o0qp |
-| Array Fields                | https://codesandbox.io/s/6j1760jkjk |
-| Async Field Validation      | https://codesandbox.io/s/m5pj55yj7x |
-| Normalize/Format/Mask Field | https://codesandbox.io/s/387z7njwzp |
+| Custom Input                | https://codesandbox.io/s/72j69vnk1x |
+| Controlled Input            | https://codesandbox.io/s/j36w7xkk7w |
 | Default/Initial Form Value  | https://codesandbox.io/s/l3mxpvmm9  |
-| ValidationSchema            | https://codesandbox.io/s/928po918qr |
 | Dirty/Touched/Submitted     | https://codesandbox.io/s/7o2wrp86k6 |
+| Normalize/Format/Mask Field | https://codesandbox.io/s/387z7njwzp |
+| Register Error Messages     | https://codesandbox.io/s/o766kp4z05 |
+| ValidationSchema            | https://codesandbox.io/s/928po918qr |
 | Validation On Blur          | https://codesandbox.io/s/w7p3km6nyw |
 | Validation On Change        | https://codesandbox.io/s/74zw1oqozx |
-| Controlled Input            | https://codesandbox.io/s/j36w7xkk7w |

examples/customValidation.tsx

@@ -0,0 +1,88 @@
+import React from "react";
+import ReactDOM from "react-dom";
+import useForm from "react-hook-form";
+
+import "./styles.css";
+
+function App() {
+  const { register, handleSubmit, errors } = useForm();
+  const onSubmit = data => {
+    alert(JSON.stringify(data));
+  };
+  const intialValues = {
+    firstName: "bill",
+    lastName: "luo",
+    email: "bluebill1049@hotmail.com",
+    age: -1
+  };
+
+  return (
+    <div className="App">
+      <form onSubmit={handleSubmit(onSubmit)}>
+        <div>
+          <label htmlFor="firstName">First Name</label>
+          <input
+            defaultValue={intialValues.firstName}
+            name="firstName"
+            placeholder="bill"
+            ref={register({
+              validate: value => value !== "bill"
+            })}
+          />
+        </div>
+        {errors.firstName && <p>Your name is not bill</p>}
+
+        <div>
+          <label htmlFor="lastName">Last Name</label>
+          <input
+            defaultValue={intialValues.lastName}
+            name="lastName"
+            placeholder="luo"
+            ref={register({
+              validate: value => value.length > 3
+            })}
+          />
+        </div>
+        {errors.lastName && <p>Your last name is less than 3 characters</p>}
+
+        <div>
+          <label htmlFor="email">Email</label>
+          <input
+            defaultValue={intialValues.email}
+            name="email"
+            placeholder="bluebill1049@hotmail.com"
+            type="email"
+            ref={register}
+          />
+        </div>
+
+        <div>
+          <label htmlFor="age">Age</label>
+          <input
+            defaultValue={intialValues.age}
+            name="age"
+            placeholder="0"
+            type="text"
+            ref={register({
+              validate: {
+                positiveNumber: value => parseFloat(value) > 0,
+                lessThanHundred: value => parseFloat(value) < 200
+              }
+            })}
+          />
+        </div>
+        {errors.age && errors.age.type === "positiveNumber" && (
+          <p>Your age is invalid</p>
+        )}
+        {errors.age && errors.age.type === "lessThanHundred" && (
+          <p>Your age should be greater than 200</p>
+        )}
+
+        <button type="submit">Submit</button>
+      </form>
+    </div>
+  );
+}
+
+const rootElement = document.getElementById("root");
+ReactDOM.render(<App />, rootElement);

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-hook-form",
-  "version": "3.2.4",
+  "version": "3.2.5-beta.3",
   "main": "dist/index.js",
   "module": "dist/index.es.js",
   "types": "dist/index.d.ts",

src/logic/validateField.ts

@@ -135,10 +135,10 @@ export default async (
           values.reduce(async (previous, [key, validate], index): Promise<ValidatePromiseResult> => {
             const lastChild = values.length - 1 === index;
 
-            if (isEmptyObject(previous) && typeof validate === 'function') {
+            if (typeof validate === 'function') {
               const result = await validate(fieldValue);
 
-              if (result !== undefined) {
+              if (typeof result !== 'boolean' || !result) {
                 const data = {
                   type: key,
                   message: isString(result) ? result : '',